Precise and quick positioning of an object having six degrees of freedom in space, represented by a silicon table and mask table of a lithography machine, is a necessary condition for implementing the precise movement control of the object. Currently, the object positioning in a space generally adopts a photoelectric encoder, a grating ruler, a magnetic encoder, a ultrasonic sensor, a vision sensor, a quadrant, an electric eddy current sensor, a laser interferometer and a laser ranging sensor, etc., but in positioning systems constituted by these sensors, either the sensor has a cable connection (the cable inevitably interferes with movement precision), or the positioning system has disadvantages of high cost and large volume. Therefore, there is desperately needed a contactless system for positioning an object in space without a cable connection while having characteristics of great positioning precision, expedited response, simple structure, and reduced cost.